Sunni-Shiite tensions escalated in Yemen on Friday when Houthi rebels, who are Shia, clashed with members of al Qaeda. At least 10 people were killed in the fighting in the central part of the country. The clashes between the two groups signaled the expansion of the sectarian infighting that has ravaged much of the country in the last few weeks.

Houthi fighters attempted to enter the town of Radda in al-Bayda province, Al Jazeera reported. The Shiite fighters were stopped from entering the town when Ansar al-Sharia, an al Qaeda-linked Sunni militant group, blocked the main road. The clashes on Friday follow days of infighting between the tw...